A metal flange electrical insulation detection device

Abstract

The present invention provides a metal flange electrical insulation detection device, which belongs to the field of corrosion protection. The detection device includes a blocking electrode, a signal superposition module, a signal measurement module, an AC excitation module, a DC excitation module, and a program control module. Aiming at the problem that the electrical insulation performance of the insulating material of the heterogeneous metal flange connection structure is difficult to detect during use, the present invention adopts a blocking electrode method, and measures the electronic conductivity and ion conductivity of the insulating material through AC and DC impedance testing, and then determines the absolute value of the electronic conductivity and ion conductivity per unit area or the ratio of the electronic conductivity to the ion conductivity, so as to evaluate the electrical insulation performance of the insulating material in the metal flange connection structure, warn of the occurrence of galvanic corrosion, and solve the problem of inaccurate detection results of electrical insulation performance indicators and unclear classification and grading indicators in the metal flange connection structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion protection, and in particular relates to an electrical insulation state detection device for a dissimilar metal flange connection structure and a use method thereof. Background Art

[0002] Galvanic corrosion between dissimilar metals usually occurs in dissimilar metal connection structures, which leads to accelerated corrosion of the anode metal material, resulting in corrosion failure of the connection structure, seriously affecting the safety of the connection structure. In various engineering practices, it is inevitable to use a variety of metal materials and various connection methods to achieve specific functions. In order to eliminate the adverse effects caused by galvanic corrosion, insulating materials are usually used to physically isolate the two metals at the dissimilar metal connection parts to block the path so that galvanic corrosion cannot occur.

[0003] However, in actual use, the insulating material ages under the influence of the environment, the electrical insulation performance decreases, the electronic conductivity increases, and the electronic circuit is formed between the dissimilar metals, resulting in galvanic corrosion. As time goes by, the electrical insulation performance will drop significantly, causing the galvanic corrosion to become more serious, which in turn affects the reliability of the dissimilar metal connection structure, resulting in leakage, bubbling, dripping, and leakage. The aging process of the insulating material between dissimilar metals is affected by many factors such as the connection structure, the type of dissimilar metals, and the environmental medium conditions. The electrical insulation performance is difficult to detect and characterize, and the insulation state cannot be accurately grasped. Early warning of galvanic corrosion is impossible. Once obvious corrosion occurs, the anode metal material has been severely corroded and can only be repaired and replaced, causing huge economic losses, and easily causing corrosion-related accidents, seriously affecting the use of equipment and factory production.

[0004] In order to timely and accurately grasp the corrosion and aging status of insulating materials and guide the maintenance and use of dissimilar metal connection structures in production practice, a large amount of research work has been carried out both at home and abroad, and a variety of technical approaches have been proposed to detect and evaluate the electrical insulation status. Chinese patent CN202010948585.5 proposes a device for monitoring electrical insulation between dissimilar metals and a method for monitoring electrical insulation status under working conditions. By bypassing parallel resistors, a zero-resistance ammeter is used to monitor the galvanic current, and the electrical insulation state is judged by the size of the galvanic current, thereby realizing the evaluation of corrosion resistance. Chinese patent CN201510921271.5 proposes a method for monitoring the insulation state of dissimilar metals in a conductive solution. The method of parallel bypass resistors is also used to realize the division of different insulation levels between dissimilar metals. Chinese patent CN201710067933.6 proposes a device and method for monitoring the insulation state of galvanic couples. By switching units, the detection resistors are connected between the two metals respectively, and the current value is detected to obtain the equal insulation value curve. By comparing with the pre-stored critical equal insulation value curve, the insulation state between the two metals is judged. Chinese patent CN201710239977.2 proposes an insulation status monitoring device based on voltage measurement to obtain insulation contour lines, and judges the insulation status by comparing the measured insulation contour lines with the pre-stored alarm insulation contour lines. Chinese patent CN201811504021.1 proposes an online detection method for the insulation status of seawater pipelines, which uses AC impedance measurement technology to judge and grade insulation performance through spectrum curves or characteristic frequencies. Chinese patent CN202011281229.9 proposes a new electrical insulation monitoring system and method for sea valves, which reduces measurement errors by monitoring the potential difference and insulation resistance values. The above method uses different technical approaches to measure the potential difference, galvanic current, insulation impedance, etc. between dissimilar metals, and then judge and grade the electrical insulation performance. However, what is measured is the mixed effect of the entire insulation structure. The indicators used to judge the electrical insulation performance will be affected by many factors such as the type of dissimilar metal materials, the type of insulating materials, the distance between metals, the connection structure, and the environmental medium conditions. Even if the corresponding contour lines and spectrum curves are established, it is impossible to accurately distinguish the measurement results under the influence of many factors, and there are major technical deficiencies. Summary of the invention

[0005] Aiming at the problem that the electrical insulation performance of the insulating material of the heterogeneous metal flange connection structure is difficult to detect during use, the present invention adopts a blocking electrode method to measure the electronic conductivity and ionic conductivity of the insulating material through AC and DC impedance tests, and then determines the absolute values ​​of the electronic conductivity and ionic conductivity per unit area or the ratio of the electronic conductivity to the ionic conductivity, thereby evaluating the electrical insulation performance of the insulating material in the metal flange connection structure, warning the occurrence of galvanic corrosion, and solving the problems of inaccurate detection results of electrical insulation performance indicators and unclear classification and grading indicators in the metal flange connection structure.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A metal flange electrical insulation detection device directly measures the electronic conductivity and ion conductivity of the insulating material between the metal flanges, and grades the electrical insulation performance of the insulating material between the metal flanges and evaluates the insulation state through the absolute values ​​of the electronic conductivity and ion conductivity per unit area or the ratio of the electronic conductivity to the ion conductivity.

[0008] Preferably, the detection device includes a blocking electrode, a signal superposition module, a signal measurement module, an AC excitation module, a DC excitation module, and a program control module.

[0009] The blocking electrodes are connected to both sides of the insulating material to measure the electronic conductivity and ionic conductivity of the insulating material;

[0010] The signal superposition module is connected to the AC excitation module and the DC excitation module, and is used to superimpose AC and DC signals;

[0011] The signal measurement module measures and conditions the feedback current signal or voltage signal;

[0012] The AC excitation module is used to apply an AC signal to the insulating material;

[0013] The DC excitation module is used to apply a DC signal to the insulating material;

[0014] The program control module controls the measurement process through a built-in program.

[0015] When in use, the AC and DC signals of the AC excitation module and the DC excitation module pass through the signal superposition module, and then directly apply AC or DC voltage signals or current signals to the insulating material through wires and blocking electrodes. The signal measurement module measures and conditions the feedback current signal or voltage signal, and the program control module controls the measurement process through the built-in program.

[0016] Preferably, the blocking electrode is made of an inert metal material in a sheet shape and is directly attached to both sides of the insulating material when in use.

[0017] In a preferred embodiment, the blocking electrode is made of gold paste, platinum paste or gold sheet, platinum sheet.

[0018] Preferably, the frequency of the signal applied by the AC excitation module is 0.1 Hz to 500 Hz, the voltage amplitude is 10 mV to 10 V, and the voltage range of the signal applied by the DC excitation module is -10 V to 10 V.

[0019] Compared with the prior art, the metal flange electrical insulation detection device of the present invention has the following beneficial effects:

[0020] The electrical insulation detection device of the present invention directly measures the electronic conductivity and ion conductivity of the insulating material between the metal flanges, and classifies the electrical insulation performance of the insulating material between the metal flanges through the absolute value of the electronic conductivity and ion conductivity per unit area or the ratio of the electronic conductivity to the ion conductivity, and evaluates the insulation state. The present invention provides a new way for online detection of electrical insulation of metal flanges, has the characteristics of simple operation, intuitive results, and easy implementation, does not require professional technicians to participate in data analysis and judgment, and provides a simple and easy method for detection and evaluation of electrical insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 It is a schematic diagram of the metal flange electrical insulation detection device of the present invention.

[0022] The symbols in the figure represent:

[0023] 1. Blocking electrode, 2. Signal superposition module, 3. Signal measurement module, 4. AC excitation module,

[0024] 5. DC excitation module, 6. Program control module. DETAILED DESCRIPTION

[0025] Combine the following Figure 1 A metal flange electrical insulation detection device of the present invention is described in detail below.

[0026] A metal flange electrical insulation detection device of the present invention directly measures the electronic conductivity and ion conductivity of the insulating material between the metal flanges, and grades the electrical insulation performance of the insulating material between the metal flanges and evaluates the insulation state through the absolute values ​​of the electronic conductivity and ion conductivity per unit area or the ratio of the electronic conductivity to the ion conductivity.

[0027] The detection device includes a blocking electrode, a signal superposition module, a signal measurement module, an AC excitation module, a DC excitation module, and a program control module;

[0028] The blocking electrodes are connected to both sides of the insulating material to measure the electronic conductivity and ionic conductivity of the insulating material;

[0029] The signal superposition module is connected to the AC excitation module and the DC excitation module to superimpose AC and DC signals. This module uses the precision operational amplifier ADA4522 and the electronic switch ADG1419 as the core to form an adder. ADA4522 has a maximum low offset voltage of 5uV, a maximum extremely low offset drift of 22nV / ℃, and low voltage noise. The unit gain bandwidth is 3MHz, which can effectively realize the signal superposition function. ADG1419 has a 2.1Ω on-resistance and a 0.1nA leakage current, which can complete the control of AC and DC superposition.

[0030] The signal measurement module measures and conditions the feedback current signal or voltage signal; this module uses the 24-bit precision ADC chip AD7782 to realize the synchronous analog-to-digital conversion of voltage and current signals, converting the analog voltage and current signals in the loop into digital signals to provide data streams for the core processor.

[0031] The AC excitation module is used to apply AC signals to insulating materials; the AC signal of this module adopts the digital frequency synthesizer AD9833, which has flexible digital programmable frequency and phase control capabilities. It has a resolution of up to 0.01Hz and a total harmonic distortion rate of -66dBc, providing a perfect AC signal.

[0032] The DC excitation module is used to apply a DC signal to the insulating material. This module uses a high-precision 16-bit bipolar DAC chip AD5761, with a total unadjustable error of 0.1% FSR, a settling time of 7.5uS, and low voltage noise. With synchronous update function.

[0033] The program control module controls the measurement process through the built-in program. This module uses the STM32F746IG with ARM Cortex-M7 core as the main CPU control. The main frequency is up to 217MHz, and it has dedicated processing instructions for the single-precision floating-point processing unit DSP to accelerate digital signal processing. The CPU integrates 1Mbyte high-speed FLASH program memory and 320Kbytes SRAM memory, and has multiple low-power operation modes.

[0034] When in use, the AC and DC signals of the AC excitation module and the DC excitation module pass through the signal superposition module, and then directly apply AC or DC voltage signals or current signals to the insulating material through wires and blocking electrodes. The signal measurement module measures and conditions the feedback current signal or voltage signal, and the program control module controls the measurement process through the built-in program.

[0035] The blocking electrode is made of an inert metal material and is in a sheet shape. When in use, it is directly attached to both sides of the insulating material.

[0036] The blocking electrode is made of gold paste, platinum paste or gold sheet, platinum sheet.

[0037] The frequency of the signal applied by the AC excitation module is 0.1 Hz to 500 Hz, and the voltage amplitude is 10 mV to 10 V. The voltage range of the signal applied by the DC excitation module is -10 V to 10 V.

[0038] Specifically, during measurement, the AC excitation module applies an AC excitation signal with a frequency of 135Hz and a voltage amplitude of 5V to the blocking electrode. The signal measurement module detects the current signal flowing through the loop and calculates the total conductivity of the insulating material. Then, the DC excitation module applies a DC excitation signal with a voltage of 5V. The signal measurement module detects the current signal flowing through the loop and calculates the electronic conductivity of the insulating material. The insulation state of the insulating material is graded and evaluated according to the electronic conductivity or the ratio of the electronic conductivity to the total conductivity.

Claims

1. A metal flange electrical insulation detection device, characterized in that: The device directly measures the electronic conductivity and ion conductivity of the insulating material between the metal flanges, and classifies the electrical insulation performance of the insulating material between the metal flanges and evaluates the insulation state through the absolute values ​​of the electronic conductivity and ion conductivity per unit area or the ratio of the electronic conductivity to the ion conductivity. The detection device includes a blocking electrode, a signal superposition module, a signal measurement module, an AC excitation module, a DC excitation module, and a program control module. The blocking electrodes are connected to both sides of the insulating material to measure the electronic conductivity and ionic conductivity of the insulating material; The signal superposition module is connected to the AC excitation module and the DC excitation module, and is used to superimpose AC and DC signals; The signal measurement module measures and conditions the feedback current signal or voltage signal; The AC excitation module is used to apply an AC signal to the insulating material; The DC excitation module is used to apply a DC signal to the insulating material; The program control module controls the measurement process through a built-in program; When in use, the AC and DC signals of the AC excitation module and the DC excitation module are directly applied to the insulating material through the wire and the blocking electrode after passing through the signal superposition module. The signal measurement module measures and conditions the feedback current signal or voltage signal, and the program control module controls the measurement process through the built-in program. The blocking electrode is made of an inert metal material and is in a sheet shape. When in use, it is directly attached to both sides of the insulating material.

2. A metal flange electrical insulation detection device according to claim 1, characterized in that: The blocking electrode is made of gold paste, platinum paste or gold sheet, platinum sheet.

3. A metal flange electrical insulation detection device according to claim 1, characterized in that: The frequency of the signal applied by the AC excitation module is 0.1 Hz to 500 Hz, and the voltage amplitude is 10 mV to 10 V. The voltage range of the signal applied by the DC excitation module is -10 V to 10 V.

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